What makes some plants resistant to flooding?

By Chrissy Sexton Earth.com staff writer

Due to climate change, the frequency of extreme weather phenomena, such as droughts, fires, or floods has significantly increased. Floods have a highly negative impact on agriculture, with scientists estimating that about 15 percent of global crop losses are due to flooding. 

However, an international team of experts has now found that a signaling molecule can make plants more resistant to flooding: the gaseous plant hormone ethylene causes plants to switch on a type of emergency power system helping them survive the lack of oxygen during flooding.

Plant species differ greatly in their ability to withstand long periods of flooding. “In the case of potatoes, the roots die after two days due to a lack of oxygen. Rice plants are much more resistant, able to survive their entire lives in waterlogged paddy fields,” explained study co-author Sjon Hartman, an expert in Plant Biology at the University of Freiburg

Professor Hartman and his colleagues used Arabidopsis thaliana – a model organism for plant research – to examine how plants cope with flooding conditions. By placing Arabidopsis seedlings in a bell jar without light or oxygen and exposing them to ethylene gas, they found that the plants stopped root growth and switched energy production in the cells to oxygen-free metabolic processes. 

Moreover, the ethylene also seemed to protect the cells against harmful oxygen radicals which accumulate in oxygen-deprived plants.

“Plants notice that they are surrounded by water because the gas ethylene, which all plant cells produce, can no longer escape into the air,” said Professor Hartman. “Taken together, these rearrangements that ethylene triggers improve plant survival during and after flooding. As we better understand these signaling pathways, we can learn to make crops more resilient to flooding to combat climate change.”

Further research is needed to identify which species of plants are using these flood survival mechanisms, and to clarify how such processes could be artificially reproduced by scientists to improve the resilience of species that are less adapted to extreme weather conditions. 

The study is published in the journal Plant Physiology.